Work on the cloning of the chitin synthetase gene (CHS1) of Saccharomyces cerevisiae, in collaboration with the laboratory of P.W. Robbins, at the Massachusetts Institute of Technology, was continued. It has been confirmed that the cloned gene codes for the synthetase protein. It has also been found that strains harboring a disrupted CHS1 gene are viable and have a normal chitin content. This result suggested the presence of another chitin synthetase, which was subsequently found and characterized. Studies on the dissociation of fungal Beta(1 to 3)glucan synthetase into two fractions, one of which appears to interact with guanosine nucleotides, have been pursued further. The interaction with GTP-Gamma-S has been demonstrated in different ways. The results have been extended to S. cerevisiae, whose soluble component is not under purification.